They'll both handle the range, if ya know em. Take the two of them.
I doubt if you're gonna see a bear at over 75 yards in the eastern woods. They generally don't run around in open fields. I'd use the .45-70 myself. My .308 sits there these days collecting dust, and my .45-70 easily reaches out to 300 yards. If your hunt is in early Fall, into October, you're gonna have leaves and foliage. Any shot you get should be close in.
Pete